The very forces critical to creating the three-dimensional structure of proteins are also responsible for unwanted and often dangerous protein aggregates in protein- based therapeutics. Protein aggregation occurs at every stage in the biopharmaceutical pipeline, from development, formulation, and manufacturing to shipping, storage and point of use. The FDA has advised in its 2014 Guidance for Industry that ?It is critical for manufacturers of therapeutic protein products to minimize protein aggregation to the extent possible?, while acknowledging that the technology does not currently exist to accomplish this goal, particularly in the critical sub-visible range from 100 nm to 10 microns. Thus, there is a pressing and as-yet unmet need for instrumentation that can assess the size distribution and morphology of protein aggregates in this size range. This SBIR Phase II program will meet this need by developing an instrument that uses holographic video microscopy to characterize protein aggregates rapidly and reliably enough for in-line monitoring of pharmaceutical formulations. The proof-of-principle studies performed under the Phase I grant demonstrated the accuracy of holographic characterization in measuring the size and optical properties of protein aggregates, and reliably distinguishing them from silicone oil droplets or other contaminants. The Phase II work will harness these patented capabilities for automated high- throughput measurement of real-world samples. Hardware and software innovations will be required to ensure accuracy and efficacy in high-speed characterization, and to further increase the sophistication and reliability of particle differentiation even when different components are the same size. This program will also elucidate the influence of increased flow speed on the growth rate and morphology of protein aggregates. Holographic characterization of protein aggregation will provide the detailed data needed for product development, process control and quality assurance in the biopharmaceutical industry and will result in increased efficiency, safety and cost savings in the promising and rapidly growing area of protein-based therapeutics.